Well, this may sound like hindsight and beside the point to you , but no one should ever use ComboFix without the direct supervision and helpful guidance of a trained malware removal specialist. Even tho I also like to try to figure out my problems on my own, there is good reason for the disclaimer that tells you not to run CF by yourself, which you chose to ignore.
I'll give you a few. One is even tho whatever symptoms you had may have gone away, it doesn't mean necessarily that you're malware free. Malware is very sophisticated nowdays and usually add a new twist, so something else may have been added that CF didn't know about and thus wouldn't address that could possibly add yet more malware to your system.
If you had posted the proper logs and given a description of what was happening in the
HijackThis Logs and Malware Removal forum we would know better what we are dealing with. For example, there are extortionware out there that will encrypt such sensitive data that QB deals with and demand payment from you so that you can get access back. Without the hard data of the logs, that you say you have now deleted, we have very little to go on as far as hard evidence if this were to be the case.
So my suggestion as a first step is to follow the instructions in the following topic to get a HijackThis log posted:
Preparation Guide For Use Before Posting A Hijackthis Log
Give a description of your problem as you did here and we can get an idea if anything else is hanging around. We can also get input from ComboFix's author--if CF is doing something that affects other programs like QB he wants to know about it, but we need to see data from logs.
If you do so please post a link back here.
I'm far from an expert on Business apps and never run QB, but know a bit about software. So if you do want to go ahead on your own with resolving this I can tell you that CF aggressively deletes temporary files and folders (as malware uses them extensively), so the reason you're getting the errors for the repair is probably because the
.tmp files listed no longer exist.
The
Config.Msi is related to the Microsoft Installer. If reinstalling QB gave no joy, MSI may be borked and I would look into possibly reinstalling The .NET framework also as well as visiting Windows updates. IOW, get your environment working correctly and updated before attempting to install.
More info on the MSI folder here:
http://www.pchell.com/support/configmsifolder.shtml
Someone else may have some better and specific ideas for you.